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Full vulnerability report · 2021
CVE-2021-43240High confidence

NTFS Set Short Name Elevation of Privilege Vulnerability

Microsoft · Windows 10 Version 1909

7.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • Exploitation requires an existing local or physical foothold with privileges.
  • EPSS is 0.56% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Microsoft Windows 10 Version 1909 and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-30184

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

NTFS Set Short Name Elevation of Privilege Vulnerability

What

NTFS Set Short Name Elevation of Privilege Vulnerability

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

What

NTFS Set Short Name Elevation of Privilege Vulnerability

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
local access → vulnerable operation → gain additional privileges
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
Privilege escalationPublic exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2025-2220Microsoft Windows und Microsoft Windows Server: Mehrere Schwachstellen

Ein entfernter, anonymer, authentisierter oder lokaler Angreifer kann mehrere Schwachstellen in Microsoft Windows und Microsoft Windows Server ausnutzen, um einen Denial of Service Zustand zu verursachen, seine Privilegien zu erhöhen, vertrauliche Informationen offenzulegen und beliebigen Code auszuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20211222Security Bulletin 22 Dec 2021

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 22 Dec 2021, published on 22 December 2021. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2021-AVI-959Multiples vulnérabilités dans Microsoft Windows

d?id=CVE-2021-43231 Référence CVE CVE-2021-43232 https://www.cve.org/CVERecord?id=CVE-2021-43232 Référence CVE CVE-2021-43233 https://www.cve.org/CVERecord?id=CVE-2021-43233 Référence CVE CVE-2021-43234 https://www.cve.org/CVERecord?id=CVE-2021-43234 Référence CVE CVE-2021-43235 https://www.cve.org/CVERecord?id=CVE-2021-43235 Référence CVE CVE-2021-43236 https://www.cve.org/CVERecord?id=CVE-2021-43236 Référence CVE CVE-2021-43237 https://www.cve.org/CVERecord?id=CVE-2021-43237 Référence CVE CVE-2021-43238 https://www.cve.org/CVERecord?id=CVE-2021-43238 Référence CVE CVE-2021-43239 https://www.cve.org/CVERecord?id=CVE-2021-43239 Référence CVE CVE-2021-43240 https://www.cve.org/CVERecord?id=CVE-2021-43240 Référence CVE CVE-2021-43244 https://www.cve.org/CVERecord?id=CVE-2021-43244 Référence CVE CVE-2021-43245 https://www.cve.org/CVERecord?id=CVE-2021-43245 Référence CVE CVE-2021-43246 https://www.cve.org/CVERecord?id=CVE-2021-43246 Référence CVE CVE-2021-43247 https://www.cve.org/CVERecord?id=CVE-2021-43247 Référence CVE CVE-2021-43248 https://www.cve.org/CVERecord?id=CVE-2021-43248 Référence CVE CVE-2021-43880 https://www.cve.org/CVERecord?id=CVE-2021-43880 Référence CVE CVE-2021-43883 https://www.cve.org/CVERecord?id=CVE-2021-43883 Référence CVE CVE-2021-43893 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2021-006009複数の Microsoft Windows 製品における権限を昇格される脆弱性

Microsoft Windows 10、Windows 11、Windows Server には、NTFS Set Short Name に不備があるため、権限を昇格される脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5468MS 12월 보안 위협에 따른 정기 보안 업데이트 권고

튜너 권한 상승 취약성 Windows DirectX CVE-2021-43219 DirectX 그래픽 커널 파일 서비스 거부 취약성 Windows Encrypting File System (EFS) CVE-2021-43893 Windows EFS(파일 시스템 암호화) 권한 상승 취약성 Windows Encrypting File System (EFS) CVE-2021-43217 Windows EFS(파일 시스템 암호화) 원격 코드 실행 취약성 Windows Event Tracing CVE-2021-43232 Windows 이벤트 추적 원격 코드 실행 취약성 Windows Installer CVE-2021-43883 Windows Installer 권한 상승 취약성 Windows Kernel CVE-2021-43244 Windows 커널 정보 유출 취약성 Windows Media CVE-2021-40441 Windows Media Center 권한 상승 취약성 Windows Mobile Device Management CVE-2021-43880 Windows 모바일 장치 관리 권한 상승 취약성 Windows Mobile Device Management CVE-2021-24084 Windows 모바일 장치 관리 정보 유출 취약성 Windows NTFS CVE-2021-43240 NTFS 설정 약식 이름 권한 상승 취약성 Windows NTFS CVE-2021-43231 Windows NTFS 권한 상승 취약성 Windows NTFS CVE-2021-43230 Windows NTFS 권한 상승 취약성 Windows NTFS CVE-2021-43229 Windows NTFS 권한 상승 취약성 Windows Print Spooler Components CVE-2021-41333 Windows 인쇄 스풀러 권한 상승 취약성 Windows Remote Access Connection Manager CVE-2021-43238 Windows 원격 액세스 권한 상승 취약성 Windows Remote Access Connection Manager CVE-2021-43223 Windows 원격 액세스 연결 관리자 권한 상승 취약성 Windows Remote Desktop CVE-2021-1669 Windows 원격 데스크톱 보안 기능 우회 취약성 Windows Shell CVE-2020-0655 원격 데스크톱 서비스 원격 코드 실행 취약성 Windows Storage CVE-2021-43235 저장소 공간 컨트롤러 정보 유출 취약성 Windows Storage Spaces Controller CVE-2021-43227 저장소 공간 컨트

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 15 Dec 2021 · Last source change 4 Aug 2024, 03:55 UTC · CWE not yet assigned

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-30184
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD modified after enrichment

Missing structured fields: CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2021-30184↗CISA Vulnrichment SSVC evidence↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-43240 · cve.blacktree.nl